Regulating apparatus



* 13, 1938.. J. F KOVALSKY' 2,?l4,333

REGULATING APPARATUS Filed Nov. 8, 1934 WITNESSES:

INVENTOR Z P i Patented Dec. 13, 1938 UNITED STATES REGULATING APPARATUS Joseph F. Kovalsky, Turtle Creek, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 8, 1934, Serial No. 752,069

9 Claims.

My invention relates to electrical regulatin systems and it has particular relation to improved means for preventing hunting in regulating systems wherein a contact-making type of quantityresponsive control element is utilized.

Recognized desirable performance characteristics of present-day regulators, practically all of which require the use of anti-hunting means to prevent an overshooting of their corrective actions, are high sensitivity and relatively rapid response. The functioning of anti-hunting means of all typeswhich within my knowledge have in the past been utilized has, for reasons to be made evident presently, seriously restricted the upper limits of sensitivity and speed of response which regulating systems using control devices of the contact-making type in practice are capable of attaining. It is to the overcoming of such difllculties that the present invention is directed.

Generally stated, the object of my invention is to improve the performance characteristics of electrical regulators of the type referred to above.

A more specific object of my invention is to provide anti-hunting means which impose no objectionable limitations upon the performance characteristics of such regulators.

Another object of my invention is to provide anti-hunting means which effectively stabilize regulatory actions without impairing the speed of response or the sensitivity of the contact making control device which forms a part of the regulating system.

A further object is to provide a-form of antihunting means in which the practically attainable range of anti-hunting force values is greatly broadened.

In prior art anti-hunting systems, suitable for application to quantity-responsive control means of the contact making type, the desirable stabilizing effect has been attained by directly modifying the action of the movable contactcarrying arm which is positionally responsive to the regulated quantity. In one scheme extensively applied in the past, contact engagement has operated to so recalibrate the control device as to urge the movable arm in the opposite direction tothereby prematurely interrupt the corrective action. In many applications, a change in such calibration of the orderof at least 10% has been found essential to produce the desired stability.

In control devices of the contact making type, it is recognized that the sensitivity may be increased by reducing the friction to movement of the device parts, increasing the forces which pro-' duce such movement in accordance with changes in the regulated quantity, and restricting to a low magnitude the range through which the movable contact member must travel to efiect the engagement with the cooperating stationary contact members. It is likewise known that the speed of response may in turn be raised by minimizing the weight of the moving parts to reduce their inertia and also by decreasing the customary damping action, the direct effect of which is to slow down the rate of movement.

When applying to such control devices the prior art anti-hunting systems, either the 'gap of contact travel must be substantially widened to prevent the movable contact from being biased by the stabilizing force into engagement with the opposing or non-initially engaged stationary member, or else objectionably heavy damping must be applied to the movable member actuating structure to achieve the same result. In practice,

both of these expedients are usually resorted to, and as a consequence, the speed of response of the control device is diminished to but a small percentage of which it otherwise might be. Likewise, the sensitivity is also reduced to a value much lower than it could be made were the antihunting forces not to be exerted upon the movable contact actuating means.

I have discovered that the above pointed out disadvantages of prior art anti-hunting systems may be largely eliminated by causing the stabilizing impulses or forces to act upon the heretofore stationary contact members of the control device instead of upon the movable contact carrying arm as in the past. In the practice of my invention, therefore, I utilize such an arrangement and have found that it not only permits the desired narrow gap of movable contact travel to be retained in the interests of sensitivity, but also it allows the damping action, previously considered highly essential, to be almost completely dispensed with, and thus likewise substantially enhances the speed of response. Inasmuch as the range of travel I of the heretofore stationarily mounted contact members which are specially biased in accordance with the teaching of my invention may be made practically without limit. a

hunting means of my invention applied to the contact-making control device comprised by a generator voltage regulator, and

Fig. 2 is a diagrammatic representation of a modified form of anti-hunting system suitable for application to the contact making control device shown in Fig. I.

Referring to the drawing and particularly to Fig. 1 thereof, the regulating system there depicted is adapted to maintain constant the voltage of an electrical generator l0, the armature windings l2 of which are directlyconnected to the conductors I 4 of an output circuit'and the field winding l6 of which is connected to receive exciting current from a suitable source 01' directcurrent voltage shown in the form of a separate excitor l8. To adjust the machine exciting current for the purpose of controlling the machine voltage Ex, a rheostat 20 is connected in the excitation supply circuit and arranged to be operated by an electric motor 22 which is respectively controlled in its voltage lowering and raising directions by a pair of relay devices L and R.

For the purpose of selectively controlling the actuation of these two relays in accordance with changes in the magnitude of the regulated voltage, a contact making control device 28 is utilized. As shown, this device comprises a quantity change responsive solenoid 30 which is energized by the voltage E1: to be regulated and which serves to exert upon a contact carrying arm 32 an upwardly acting force which is opposed by the downwardly acting force of a tension spring 34.

When the regulated voltage is of the desired value, these two forces so balance each other that the movable contact member 36 of the device is biased to the neutral or mid-position shown. A decrease in voltage Ex allows the arm 32 and a contact member 36 which it carries to move downwardly into engagement with a cooperating member R to complete, from a battery 40 or other suitable energizing source, a circuit which actuates relay R into its closed contact positibn. In this position, a contact member 42 of the relay completes from an energizing source 44, also shown in the form of a battery, a circuit for driving rheostat operating motor 22 in the generator-voltage raising direction.

In a similar manner, when voltage Er rises above the desired value, contact member 36 of the control device 28 is moved upwardly into engagement with a second cooperating member L to complete an actuating circuit for motor control relay L. This relay completes, through a contact member 48, a circuit for energizing the motor 22 in its voltage lowering direction, and thus causes the voltage of generator Hi. to be corrected back to the desired value.

The improved anti-hunting means of my invention will now be described in connection with the voltage-regulating system just explained. It may here be pointed out, however, that these improved means are in no way restricted to that or any other particular system, since they are capable of application whenever a contact-making control device is utilized to maintain constant a quantity, such as temperature, pressure, or the like, which is capable of adjustment.

In the regulating system illustrated in Fig. l, I achieve the desired anti-hunting action by mounting the two contact members L and R of the control device 28 upon movable carrying arms 50 and 52. As illustrated, these arms are pivoted at their left ends and are biased, by means of a amazes tension spring 54, toward a pair of stationary stop members 56. These stops are positioned to make the gap between the members L and R, through which the movable contact member 36 travels. of the relatively small or narrow value essential to the desired high degree 01 regulator sensitivity.

In association with each of the arms 33 and 52, I place a solenoid device, shown at 53 and 33,

which upon energization, draws'the arm away from its cooperating stop 5, and thus increases the gap of movable contact travel. Device 53 has its energization controlled by means of an auxiliary contact member 32 carried by the voltage raising control relay R, while device 63 is similarly controlled by an auxiliary contact member 64 which forms a part of voltage lowering control relay L.

In operation of the described anti-hunting means, when, for example, in response to a drop in the regulated quantity Er, the quantity-responsive control device 28 effects an engagement of contact member 36 with member R, the resulting actuation of the quantity-raising control relay R completes from battery 40, through auxiliary contact member 62, a circuit which energizes the stabilizing solenoid 58. This solenoid then draws the contact member R. away from the'cooperating movable member 36 at a rate of speed which may be controlled in any one of a number of different manners as for example by the use'of a dashpot, such as indicated at 68. As a result of this separation, the corrective action is so prematurely interrupted as to eiiectively prevent overshooting oi the regulated quantity Ex.

A similar action takes place upon the engagement of device contact member 36 with member L, in which case auxiliary contact member 84 of the quantity lowering relay L is caused to complete a circuit for energizing the stabilizing solenoid 60, which solenoid draws contact member L away from the member 36 to properly prematurely arrest the corrective quantity lowering action.

Through a utilization of this improved antihunting arrangement, it will be apparent that the normal gap of travel of the control device movable contact member 36 may be made exceedingly narrow and the sensitivity 01' the device thereby correspondingly raised. Likewise, since the stabilizing forces act upon the cooperating and previously stationary contact members L and R, instead of upon this movable member, the previous need for heavy damping means to slow down the movement of the contact carrying arm 32 of the device is almost completely eliminated. The resulting permissible dispension with such means causes the rate of response also to be materially raised.

Some idea of the magnitude of these respective improvements may be gained from the following test data obtained from a representative quantity-responsive contact-making control device utilized in a voltage regulating system of the type shown in Fig. 1. When adjusted to give its best performance, the control device equipped with the anti-hunting means of this invention exhibited a sensitivity of 0.5%, while that equipped with the prior art means had a sensitivity of 1.00%. When the load on the regulated generator changed by 8%, the system employing my improved anti-hunting means showed a speed of response of 4 of a second, while that employ ing the prior art type of anti-hunting required V; of a second to similarly respond. In both 7 determined special variety of anti-hunting may be desired, and for the purpose of providing such the equipment illustrated in Fig. 2 may be utilized. This apparatus is basically similar to that shown in Fig. 1, it comprising in addition a timing device 10, which may be in the form of thermal, electronic, motor or induction apparatus, so connected in the energizing circuits of the stabilizing solenoids 58 and 60 as to intermittently energize these circuits at a relatively slow frequency of the general order of about one energizing and interrupting cycle per second.

The timing device shown is in the form of an electrically actuated relay mechanism, the solenoid winding 'IZof whichreceives energizing current through a circuit which includes a contact member 16. By virtue of such energization, a plunger member 14 of the device is slowly moved upwardly thereby causing, after an appropriate delay, the contact member 16 to interrupt this winding energizing circuit. The plunger member then returns to the original lower position in which contact member I6 reestablishes the circuit,

and the cycle just described thus continues to repeat itself.

In the circuit shown this same contact member 16 is utilized to control the energization of the stabilizing solenoids 58 and 60. These solenoids are so designed that when energized they move their associated contact members R and L away from the cooperating member 36 of the device 28 at a relatively slow rate. When deenergized the spring 54 is allowed to return these members to their original or starting position.

Thus for small errors in the regulated quantity, the contacts of device 28 are intermittently closed for recurring'short periods of time, and there results an intermittent form of corrective control action the individual impulses in which are proportional to the magnitude of the errorin the regulated quantity. However, when a large error or deviation in the regulated quantity occurs, the movable contact 36 will continuously follow the periodically receding contact member R or L, and thereby maintain continuous contact.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefre,'is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended-claims.

I claim as my invention:

1. In a regulating system comprising a control device having a pair of contact members one of which is positionally responsive to a quantity to be regulated and the other of which is engaged by the first when said quantity varies from a desided value, in combination, means sensitive to the engagement of said members for adjusting the magnitude of said quantity, the combination of means adapted to maintain said second-named contact member in'an unvarying stationary position when no quantity-correcting operation is in progress, and means for moving it away from the one first named contact-member upon the occurence of each quantity-correcting operation thereby to interrupt said operation.

2. In a regulating system comprising a control device having a pair of contact members one 01' which is positionally responsive to a quantity to be regulated and the other of which is engaged by the first when said quantity varies from a desired value, in combination, a relay sensitive to the engagement of said members, and means controlled by said relay for adjusting the magnitude of said quantity, means adapted to maintain said second-named contact member in an unvarying stationary position when said --relay is unenergized, and means for moving it away from the member first named upon energization of the relay to interrupt the regulating action prior to a completion in the correction of the regulated quantity.

3. In a regulating system comprising a control device having two positionally separated contact members and a cooperating third member adapted to engage the one or the other of the members first named upon variations from a desired value in a quantity to be regulated, and means sensitive to the engagement of said device contacts for adjusting the magnitude of said quantity, the combination of means adapted to maintain said first-named members in unvarying sta tionary positions when no quantity-correcting operation is in progress, and means operative upon the occurrence of quantity-correcting operations which result from their engagement by the third members to move the first-named member then engaged away from said third member thereby to interrupt said operations.

4. In a regulating system comprising a control device having two positionally separated contact members and a cooperating third member adapted to engage the one or the other of the members first named when a quantity to be regulated varies from a desired value, a pair ofrelays selectively sensitive to said engagements and means responsive to the actuation of said relays for adjusting the magnitude of said quantity, the combination of means adapted to maintain said first-named members in unvarying stationary positions so long as said relays remain en ergized and means actuated upon relay energization which results from engagement by the third member of one of the contact members first named to move that member away from said third member thereby to interrupt the resulting quantity-correcting operation.

5. In a regulating system, in combination, an electric machine to be regulated, a primary relay having contact meanspositionally responsive to a characteristic of the machine to be regulated, and

contact means cooperatively related thereto and normally biased to a given position, motor operated means for controlling said regulated quantity, secondary control relay means responsive to the engagement of said primary relay, co0perating contact means for controlling said motor operated means, and electromagnetic means energized upon operation of said primary relay to a circuit closing position for abruptly moving said second named contact means in a direction away from said first named contact means, and means for permitting a gradual return only of said sec-- ond named contact means to said given position upon deenergization of said electromagnetic means.

6. In a regulating system, in combination, an electric machine to be regulated, a primary control relay having contact members movable in accordance with variations in a characteristic of the machine, and contact members cooperatively related to said first named contact member and normally biased to predetermined stationary positions, means controlled by engagement of said cooperating contact members for effecting a correction in the regulated quantity, and electro- 7 responsive anti-hunting means actuated upon the initiation of a corrective action for abruptly moving said normally stationary contact memhere in a direction away from the first named contact members, said anti-hunting means in-.

sponsive means energized upon operation of said secondary relay to its circuit closing position for abruptly moving said second named contact means in a direction away from said first named contact means, and retardation means for permitting a. gradual return only of said second named contact means to the given position upon operation of said secondary relay to its deenersized position.

8. In an electrical system to be regulated, in

combination, a control relay having contact members positlonally responsive to an electrical quan- 7 tlty of the system, and contact members normally biased to given positions andadapted to cooperate with said first named contact members, means actuated upon engagement of said cooperating contact members to control the regulated quantity, means actuated upon engagement of said cooperating contact members for abruptly moving said secondnamed contact members in a direction away from said first named contact members, and damping means for permitting a gradual return only of said second named contact members to said given positions after separation of said cooperating contact members.

9. In an electrical system to be regulated, in combination, a control relay having contact means positionally responsive to an electrical quantity of the system, and contact means cooperatively related thereto and normally biased to a given position, means responsive to the engagement of said cooperating contact means ior controlling said regulated quantity, anti-hunting means comprising electroresponsive means energized upon engagement of said contact means for abruptly moving said second named contact means in a direction away from said first named contact means, and movement damping means for permitting a. gradual return only 01' said second named contact means to its initial position upon deenergization of said electroresponsive means.

JOSEPH F. KOVALSKY. 

